Catalytic desulfurization and cracking of sulfur-containing petroleum



Nov. 7, 1950 J. E. FORD, JR 2,528,586

CATALYTIC DESULFURIZATION AND CRACKING 0F SULFUR-CONTAINING PETROLEUMFiled June 3, 1947 ASPHALT fdl INVENTOR.

? da@ E img C@ BY JM WMA Patented Nov. 7, 1950 y 2528586 cArALYTIcDEsULFURlzA'rIoN AND CRACKING OF SULFUR-CONTAIN- ING PETROLEUM Jo'hE.Ford, -Jr., Garden city, N. Y., assigner to HoudrProcess Corporation,Wilmington, Del., a corporation of DelawareV "I Application June 3,1947, Serial No. 752,211

This invention' relates to the conversion of hydrocarbon `material touseful products and is especially directed to the productionofhydrocarbon products,.such 4a, engine fuels, fuel oil,

kerosene and the like.4 This invention involves the processing of crudehydrocarbon oils hav 7 claims." (c1. 19e- 50) Y 2 of the light fraction,and in the other of which conversion zones a major amount of the totalfreshly regenerated active cracking catalyst coning high sulfurcontents, such as sour crude oils,

to yield products of sulfur contents Many crude petroleum: oils havesufficiently Vcoxnnnercially acceptable high sulfur content that thevarious products,

such as gasoline or diesel fuel, 'produced by distillation of the crudeoil have sulfur contents that are commercially unacceptable orundesirable and generally must be'treated separately, as by expensivechemical methods, to reduce the sulfur content. Chemical methodsfrequently are useful only to effect a reduction in sulfur content andmay cause a substantial reduction in yield of the finished product.Existing catalytic or extraction methods for the reduction of sulfurcontent involve the considerable expense incident to a separate process;In the case of diesel fuel, prior processes have been either expensiveto operate or have resulted in depreciation of this material as a fuelfor diesel engines. Indeed, the problem of sulf-ur content is notconfined to fractions having high sulfur contents since' many straightrun gasolines have a low content of sulfur, such as 0.03 to 0.10 percent (by weight), which, although low, is sufficient to influence thelead susceptibility and therefore results in an uneconomical use oftetraethyllead.

Moreover, some sulfur-containing crudes have Va corrosive effectgonthewreflnery equipment due to the sulfur compounds either originallypresent or formed during the rening.` Such crudes generally but notalways fall in the category Yof' crudes having a sulfur content ofgreater than 1.0 percent by weight of`sulfur in the 400 to l000 F.fraction and will be referred to herein as high sulfur or sourcrudes. Itshould be -understood, however, that the types and effect of the sulfurcompounds present vary lfrom crude to crude and that, although the aboveclassification is convenient, the present' invention in-Vv cludes theprocessing of crudes which have lower sulfur contents butV which behaveas souricrudes.

It has now been found, in accordance with'the invention, thatimprovements and economies in 1 the operation of cracking systemsemploying movingr catalysts result by employing freshlyregenerated uentactive cracking catalyst of the type described below-in two conversionzones, in one of which conversion zones a minor amount, of thetotalfreslcly regenerated catalyst contacts a normally liquid lightstraight run fraction ofa cru-'ie petroleum oil, which light fractionhas an obiectionable amount o f sulfur, under mild f tacts a heavyhydrocarbon fraction, such as a gas oil or heavier, under crackingconditions and effects conversion of the heavy fraction to substantialamounts of motor gasoline. The cracking catalyst in each conversion zonepasses therethrough in a fluent state and accumulates a coke deposit asa result of the contact with the hydrocarbon material in each zone.Coked catalyst is removed severally from the two conversion zones andregenerated in a single common regeneration zone by oxidizing at least aportion lof the coke deposit on the catalyst. Catalyst in a freshlyregenerated state is then removed Vfrom the regeneration zone andconveyed to the two zones in the proper amounts.

The unitary integrated process described herein furnishes a methodwhereby a refinery can produce superior motor fuels andother petroleumproducts from virtually all of the various fractions of. a high sulfurcrude oil at a low cost. The normallyvliquid light straight r-unfraction which is processed in one conversion zone (hereafter called thedesulfurization zone for convenience, the other conversion zone beingcalled the cracking Zone) to yield products having commerciallyacceptable sulfur contents may consist of any or all of the straight runor virgin fractions boiling below about 750" F., such as gasoline,kerosene, diesel fuel or light fuel oil, and

ume'percentages unless otherwise designated).

Such gasoline has the high octane characteristic of gasoline produced bycatalytic cracking under-conventional cracking conditions (which are:much more severe than the conditions in the -desulfurization zone), andis generally above 75 octane number (clear) by the CFR-motor method. Thediesel oil fraction may be desulfurized alone or in admixture withstraight run gasoline end boiling Vpoint about 400 to 450 F.)

. obtained from the high sulfur crude oil.

Desulfurization of .the straight run gasoline from high sulfur crudes(which gasoline generconversion conditions and effects desulfurizationper cent (by weight) of sulfur and is therefore not marketable or has apoor lead susceptibility or both because of high sulfur content) underthe described conditions removes about 60 to 90 per cent of the sulfuroriginally present to yield a gasoline of high lead susceptibilty.Moreover, desulfurization of straight run gasoline of low sulfur contentsuch as 0.02 to 0.09 per cent (by weight) of sulfur, may be eilected bythe processes herein described, whereby the lead Susceptibility andfrequently octane number of such gasolinas is improved. Such a lowsulfur gasoline may be effectively desulfurized either alone or togetherwith diesel fuel cuts from a high sulfur crude oil. When the straightrun gasoline from a high sulfur crude oil is desulfurized together withthe diesel fuel cut from the same crude, the sulfur content of the finalgasoline is slightly higher although the lead susceptibility is notdepreciated. In contrast to known methods of operation, the describedmethod of operation of the desulfurization zone considerably increasesthe amount of' gasoline suitable for use in high octane motor fuels witha considerable increase in the octane-barrels of gasoline.

Since a minor amount, preferably less than 25 per cent, of the totalcatalyst circulating in the system passes through the desulfurizationreactor, this reactor is small in comparison to the cracking reactor andthe advantages of desulfurizing the light fraction can be gained withonly a small increase in the cost of the total equipment and may, in thecase of refinery installations presently having cracking andregenerating equipment, be installed at a cost which is very low incomparison to the advantages gained. Thus, in accordance with oneembodiment of the invention involving fluent catalysts employed asmoving beds in the reactors and in the regenerator, the desulfurizationreactor is a part of a unitary plant, which also comprises a relativelylarge reactor for cracking heavy hydrocarbon stock under conventionalcracking conditions for the maximum production of gasoline and aregenerator or kiln for the removal of the coke deposited on thecatalyst due to contact with the hydrocarbon material. The catalystemployed is preferably a cracking catalyst'of moderate activity asdescribed below,

such as a silica-alumina contact mass. After regeneration, the majorportion of catalyst is passed through the cracking reactor while a minorportion, preferably less than 25 per cent of the total catalyst leavingthe regenerator, is passed to the desulfurization reactor where itcontacts a light distillate fraction under mild conversion conditions,and eil'ects desulfurization of the light fraction. By maintaining a lowcatalyst to oil ratio in the desulfurization reactor (where catalyst tooil ratio is the ratio of the weight of catalyst introduced to thereaction zone per unit time to "itlrweight of oil introduced to thereaction zone per unit time; i. e., pounds of catalyst per pound of oil)a relatively large amount of light distillate is `desulfurized withoutdiverting much catalyst from the cracking reactor and thereby avoiding areduction in the charging rate of oil to the latter.

Passage of the fluent catalyst through the desulfurization reactor as amoving non-turbulent bed has advantages particularly when the lightfraction is passed countercurrently therethrough. Under theseconditions, the light fraction is charged to the less active portion ofthe catalyst and the less refractory sulfur compounds are decomposed. Asthe light fraction progresses up the catalyst bed, additional sulfurcompounds are 'decomposed until only the more refractory sulfurcompounds remain. Such compounds encounter, near and at the top of thebed,'the catalyst in a more active state. Also, if the catalyst isintroduced at a temperature higher than the average reactor temperature,the catalyst is at a higher temperature. Hence, the refractory sulfurcompounds are decomposed near the top of the bed with a minimum ofconversion of the remainder of the fraction. Moreover, such counterflowis more efficient in removing` heat when the catalyst is charged todesulfurization reactor fxilom the regenerator without intermediatecool- It has been found, in accordance with the invention, that aparticularly eective mode of operation is to maintain a relatively lowcatalyst to oil ratio, preferably less than 0.5, but greater than 0.05,such as a ratio in the range of 0.1 to 0.4, in the desulfurizationreactor, while maintaining a relatively high ratio, preferably 1.5 orgreater, but generally less than 20, such as a ratio in the rangebetween 1.8 and 5.0 in the cracking reactor. When relatively lowcatalyst to oil ratios, such as 0.1 to 0.4, are maintained in thedesulfurization reactor, a large quantity of light fraction can bedesulfurized without affecting the throughput of the cracking reactor.Thus, for example, equal amounts of light and heavy fractions can becharged to the desulfurization and cracking reactors while maintainingcatalyst to oil ratios of 0.4 and 1.5, respectively, in these reactors,by diverting less than 25 per cent of the total catalyst to thedesulfurization reactor. In some cases, the desulfurization reactor maybe maintained at a lower temperature than the cracking reactor; thespace rate in the desulfurization reactor is generally higher than thatin the cracking reactor although approximately the same ranges areuseful in both reactors. In the case of existing installations forcracking to whichdesulfurization reactors are added, essentially thesame throughput in barrels per day can be maintained after the additionof the desulfurization reactor as had been maintained before the changeby vchanges in the operating conditions which are within the inherentilexibility of the system.

In order to understand the invention more fully, reference should be hadto the drawing which illustrates various embodiments of the presentinvention, which invention is not, however, limited in scope thereto.These embodiments will be described in connection with operations inwhich a uent refractory catalytic contact mass in molded or aggregatedform. such as pellets or spheres, is circulated by gravity as a moving,non-turbulent bed through either or both reaction and regenerationvessels. Details of such systems, as applied to cracking operations,have been described in various published articles (see, for example,'I'he T. C. C. Cracking Process For Motor Gasoline' Production by R. H.Newton,.G. S. Dunham and T. P. Simpson, Transactions Of The AmericanInstitute Of Chemical Engineers," volume 41, page 215, April 25, 1945,and the articles there cited) and hence will not be repeated here.

The drawing, in which conventional auxiliary equipment have been omittedfor clarity, shows a schematic cracking system illustrating the refiningof a crude oil wherein a light fraction is desulfurized and a heavyfraction is cracked.

In the drawing, a catalyst of the type used in cracking operations anddiscussed more fullybelow, such as a catalytically active clay, orpreferably a low alkali content silica-alumina gel, which has beencharged to the system preferably in the form of granules, pellets, orbeads of about 3 to 8 mesh and which has been freshly regenerated, isfed by line 2 to hoppers 3 and 4 and thence by lines 5 .and 6 to acracking reactor 1 and a desulfurization reactor 8. A normally liquidlight straight run fraction prepared and preheated as described belowand having a boiling range below 750 F., is fed by line 9 todesulfurization reactor 8. fraction passes upwardly through a downwardlymoving bed of catalyst in reactor 8 under the conditions described belowand is thereby desulfurized and otherwise subjected to the action of thecracking catalyst. The desulfurized vapors together with the reactionproducts of desulfurization are removed from the reactor by means of adisengaging section (not shown) and are thence conveyed by line II to afractionator I2 for further processing.

A heavy fraction having an initial boiling point above 400 is introducedto cracking reactor i by line I3 preferably in the vapor form. Ifdesired, a fraction principally in the liquid phase may be introduced byline I4 to reactor l; fractions introduced by lines I3 and I4 beingprepared and preheated as described below. Hydrocarbon materialintroduced by lines I3 and I4 is passed downwardly with a concurrentlydownwardly moving bed of catalyst. The cracked vapors are removed fromthe reactor by means of a disengaging section (not shown) and passed byline I5 to a fractionator I6 for further processing.

The downwardly moving beds of catalyst in reactors l and 8 are strippedof high boiling hydrocarbonaceous material in standard purging sections(not shown) by means of steam introduced by lines I'I and I8, thepurging steam passing upwardly through the bed and merging with thehydrocarbon material treated. Catalyst is removed from reactors 'I and 8through appropriate draw-olf devices and passes. by lines I9 and 2I toline 22 where the catalyst streams from the two reactors are merged. Thecatalyst in line 22 is then conveyed by elevator 23 to line 24 andhopper 25. The catalyst from hopper 25 is charged to a distributiondeviceA 26 communicating with a regenerator or kiln 2l. Regenerator 2lmay be a vessel equipped with a v plurality' of burning and .coolingsections or zones,

one of which is indicatedin the broken-away section of the regenerator(see article cited above). Air is pumped by 'pump 28x to preheater 29 towhich fuel from line 30l is add-ed, Combustion of the fuel in prehe'aterZELpreheats the air to about 300 F. to 1000" F., which air passes bymanifold 32 to lines 33 and thenceto-the'various burning vsections ofthe regeneratorin amounts controlled by valves 34. If desired preheater2,9 may be 'by-passed andthe air passed directly to the kiln from thepump Ybyline 3|.; Combustion of the coke is effected by means of the airthus introduced and the spent flue gases so formed are removed by lines35 t"o\ manifold 36, thereafter The light straight run an indirect heattransfer medium, such as water,

steam, or a molten mixture of inorganic salts,

is fed by lines 38, valves 39 controlling the flow thereof. It isgenerally preferred to control the 5 amount of air and the amount ofheat transfer medium so that the temperature of the catalyst does notrise above a maximum of about 1100 F. The indirect heat transfer medium,after receiving heat in the regenerator, passes by lines 4I to manifold42 and thence to a heat recovery system 43. The indirect heat transfermedium is cooled in the heat recovery system 43 from which it is removedby line 44 and recirculated to the regenerator by pump 45. Other methodsof removing the excess heat in, regenerator 21 may be used suchasrecirculation of a portion of cooled flue gases, recirculation of aportion of cooled catalyst and the like. The catalyst after regenerationby removal of at least a portion of the coke deposit (less than 0.5 percent by weight of coke preferably being left on the catalyst) is removedfrom regenerator 21 through an appropriate draw-off device and passes byline 46 to elevator 4T which conveys the catalyst to line 2 for chargingin the hoppers 3 and 4.

The amount of catalyst diverted to reactor 8 is,

in accordance with the present invention, a'

minor portion of the total amount of catalyst circulating in the systemand is preferably less than 25 per cent and may be as low as 1 to 2 percent, depending on the amount of light fraction to be desulfurized. Asdiscussed above, when reactor 8 has been added to apre-existing system,the diversion of such a minor portion of catalyst from the main streamof catalyst passing through reactor 'i' furnishes catalyst tothedesulfurization reactor while still maintaining, after minoradjustments in the conditions of operation in cracking reactor 1, thesame throughput in reactor I as was maintained prior to the diversion.In some of such cases, it may be advantageous to increase slightly thespeed of elevator 23, this increase, however, being considerably lessthan sufficient to furnish the entire amount of catalyst employed inreactor 8.

The catalyst in hopper 4 may, if desired, be cooled by a cooling coil48. However, under some conditions of operation of reactor 8,particularly those in which an average-reactor temperature in the rangeof 800 to 900 is desired, the catalyst may be charged from line 2without cooling and may enter reactor 8 in the temperature range of .950`to 1050 and be cooled by the light straight run fraction introduced tothe reactor so that 55 the average reactor temperature is in the rangeof. 800 to 900", The light straight run fraction Whichis` introducedinto reactor 8 in the vapor Yform hasucient heat capacity relative tothat ofthecatalyst, so that the temperature of this 60 fraction is not;excessively increased, the increase being generally of the order of lessthan 100 F.,' 'such as 50 F. Such a mode of operation affords excellentcontrol of the desulfurizaltion operation and avoids local overheatingof 65 the lightgfraction with attendant over treatment or cracking.` Inthelatter instance, it is preferred to maintain moderately high spacerates (the spac'rate or space velocity being defined as the volume ofliquid hydrocarbon material 70 charged tovfthe reactor perhour referredtothe volume of catalyst present in the reactor). Such space rates"v arepreferably in the range of 1.0 to 4.

In general, the conditions of operation of re- 75 actor 8 will includeaverage reactor temperatures in the range of 700 to 900 F., space ratesin the` range of 0.5 to 5, pressures in the range of atmospheric toslightly above atmospheric, such as 25 pounds per square inch gauge, andcatalyst to oil ratios in the range of 0.05 to less than 0.5, and eithercountercurrent or concurrent flow of catalyst and hydrocarbon materialmay be employed. However, the combination of Voperating conditionsselected from the above ranges is chosen so as to eiect only mildconversion as judged by the amount of lower boiling hydrocarbonsproduced from the diesel fuel cut. Thus the eiect of selecting anoperating condition which tends to produce more severe conversion (suchas a high temperature, high pressure, low space rate, or high catalystto oil ratio) is preferably balanced or compensated for by the selectionof at least one other operating condition in the opposite sense. It istherefore preferred, in accordance with the present invention, to chooseoperating conditions so that a gas oil or diesel fuel cut boiling in therange of 400 to 7507 undergoes a con` version of less than 35 per cent,with a production of less than about 30 per cent butane-free gasolineand less than 2.0 per cent coke, based on the diesel fuel cut charged.In general, the conditions in reactor 8 are chosen so that theproduction of coke, based on the weight of light fraction comprising adiesel fuel cut charged to the reactor, is in the range of about 0.5 to2 per cent and the production of gases lighter than butanes, on the samebasis, is about 0.8 to 3.5 per cent by weight. When gasoline alone istreated, the amount of coke is lower, being in the range offabout 0.2 to1.0 per cent while the production of gases lighter than 'butane is aboutthe same or slightly lower than it is when a diesel fuel cut is charged.Generally, conditions are chosen so that the coke produced in reactor 8is preferably less than about 15 per cent of the coke produced inreactor 1. When small amounts of catalyst, such as to 10 per cent of thetotal catalyst, are diverted to reactor 8, the percentage of coke may behigher although it is preferred to choose operating conditions such thatless than 2.5 per cent coke is deposited on the catalyst in reactor 8. Y

The conditions of operation of reactor 1 are well known to the art andlie generally in the ranges of 800 to 1050 F., catalyst to oil ratiosbetween about 1.5 to 20, such as ratios in the range of 118 to 5, spacerates of 0.5 to 3 and pressures of atmospheric to about 25 pounds persquare inch gauge. The cracking operation effected in reactor 1 may beof various types; for example, the hydrocarbon material may beintroduced substantially completely in the vapor phase or princif pallyin the liquid phase or in a mixed liq,uid vapor phase, and thehydrocarbon material may pass either countercurrently or concurrentlythrough the downwardly moving bed of catalyst. These types of operationare well known to the art and further details need not be repeated here.In general, the cracking conditions will be chosen so that at least 30p'er cent, and preferably more than 35 per cent of the material chargedto reactor 1 is converted to motor gasoline. Under such conditions thecatalyst discharged from the cracking reactor generally will have acarbonaceous deposit of about 1.5 to 3.0 weight per cent based on thecatalyst.

Various catalysts, particularly siliceous cracking catalysts, may beemployed in the reactors described above. These catalysts are well knownto the art and details of their preparation need not be repeated here.Typical of these catalysts are active or acid activated clays,particularly of the montmorillonite type and synthetic gels comprisingsilica and at least one other refractory oxide; for example,silica-alumina, silica-alumina-zirconia. silica-zirconia,silica-magnesia, silica-thoria and the like. In accordance with thepresent invention, it is preferred that such catalysts be prepared orprocessed so as to yield an active cracking catalyst, such as anactivity of above 30 and preferably above 35 measured by the CAT-A test.(The CAT-A test is a commercial test used for the control of theactivity of cracking catalysts in which the catalytic activity isexpressed as the volume percentage of gasoline referred to the volume ofcharge stock, produced by cracking a standardized gas oil under standardcracking conditions. Details of this test are given in Laboratory MethodFor Determining The ActivityOf Cracking Catalysts by J. Alexander and H.E. Shimp, page R,537, National Petroleum News, August 2, 1944.)

In an embodiment of the present invention involving the processing ofsour petroleum crude oils. it is preferred to use in connectiontherewith a sulfur-resistant catalyst (i. e., a catalyst whose rate ofdecline of cracking activity is not substantially increased by thepresence of sulfur compounds in the hydrocarbon material involved).Synthetic colloidal masses having cracking activity, such as the silicacontaining gels mentioned above show such resistance in contrast tocatalysts prepared by known methods from natural clays. However, sulfurresistant catalysts may be characterized (without regard to source ormethod of preparation) by the fact that such a catalyst showssubstantially no decline in cracking activity, as measured by the CAT-Atest. when subjected to an accelerated aging test in which the sample ofcatalyst is subjected to contact with substantially pure hydrogensulfide at atmospheric pressure at a temperature of 1000 F. for twohours. By the use of sulfur resistant catalysts in accordance with theinvention, the equilibrium activity of a fluent catalytic masscirculating through the cracking and desulfurization zones is maintainedat a high lever, such as above 25 and preferably above 30, as measuredby the CAT-A test. (The equilibrium activity is the activity of the massof catalyst circulating in a fluent catalyst system and has a valuefixed by a dynamic balance between the effect of adding fresh relativelyhigh activity catalyst to replace catalyst lost or removed and theeffect of deterioration of the activity of the catalyst in use.)

In one embodiment of the present invention illustrated by an exemplaryoperation, 7500 barrels per day of a high sulfur crude oil having sulfurcontent of about 2 weight per cent and a boiling range (ASTM, Engler) ofto 1000 F. are charged by line 5| to fractiorator 52 and thereinseparated into two fractions; about 3400 barrels per day of a lightfraction (a wide-cut distillate) having an end point of about 575 to 600F., although in some instances the end point may be higher, such as upto about 750 F., and about 4100 barrels per day of a heavy fractioncomprising the rest of the crude Yoil. The wide cut distillate isremoved as an overhead product through line 53 and the heavy fraction asa. bottoms product through line 54. The wide-cut distillate may then becharged to fractionator 55 in accepte tween 50 to 250 F. but suchboiling ranges lie 5 within the limits stated. Depending upon the needsof the particular refinery, either the straight run gasoline or thestraight run diesel fuel may be sent to storage through lines 58 and 59,respectively, by means ofthe proper manipu- 1Q lation of valves 6| and92, or 6,3 and 64. Alternatively, fractionator 55 may be by-passed bymeans of proper manipulation of valves 61 and 68 and the overhead fromfractionator 52 passed by line 69 directly to line 10 fordesulfurization in 15 reactor 8.r The charge to the desulfurizationreactor, which may consist of all of the material in the crude oilboiling below '150 F., or the straight run diesel fuel, or either thestraight run gasoline alone, is passed through heating coil 1| 20 infurnace 12 and thereafter passed by line 9 to reactor 8 as previouslydescribed. The treating of straight run gasoline alone is particularlyeffective when the crude oil has a low sulfur content such as below 1.0Weight per cent. If de- 25 sired, steam from line 13, preheated to adesired temperature, may be added to the charge to the desulfurizationreactor by opening the valve 14,

the amount thus added being generally less than 25 weight per cent ofthe hydrocarbon material 30 charged to the reactor.

In the exemplary operation, the entire wide-cut distillate, preheated toa temperature between 750 and 850 F., is charged to the desulfurizationreactor which is operated at an average temperature of between 800 and'35 40 tween 0.8 and. 1.5, suchv as about '1.2. rIhe light fraction afterdesulfuriza'tion, as described above, is passed by line I intofractionator I2 in which it i-s separated into aY low sulfur gasoline,

fractionator as an overhead fraction by line 15 and thereafter isappropriately stabilized and prepared for marketing by conventionalrefining methods, such as washing "with a .solution of caustic.`Desu1furized diesel fuel is removedl 50V from fractionator I2 by line16 as a side cut while any material boiling above the diesel range isremoved from the bottom of the iraction'atorV by/ line 11. By means ofappropriate manipulation of valves 18 and 19 or.8I and v82,thedesulfurized 55 diesel fuel and the bottoms, fraction may be senteither to storage` or may be included in the charge to the crackingreactor as hereinafter described. In the exemplary operation, about 1900barrels per day of motor gasoline having a 90 per cent 60 boiling point(ASTM) of 390 F. and 1310 barrels. per day of a diesel fuel out havingl0 per cent and 90 per cent boiling points (ASTM) of about 410 and 560F., respectively, are produced. vThe motor gasoline so produced has aclear octane 65 `ter as a dicsel engine fuel` is substantiallyunchanged.

The operation effectively reduces the sul 70 The .portion of crude whichis removed from lfractionator 52 by line 54 passes by line 83 to heatingcoil 84 and a furnace 85 'in which it is flieat'ed to a temperature inthe range of 800.' to

900 Fg In addition to the portionof the crude boiling above the wide cutdistillate, the material in line 83 may alsoinclude materialdesulfurized ,in reactor 8, such as all or a portion of the desulfurlzeddiesel vfuel introduced by lines '88 and 81 to line 83, or it mayinclude the bottoms fractibn nomine-materia; desuuurizea mreactor sintroducedby lines 1.1-and 81 to line 83, or it may contain an`untreated diesel fuel or gas oil outv introduced by lines 51,88 and 81or it may con# tain a recycle gas oil cut introduced by lines 99 and 81to line 83. Thus, for example, the hydrocarbon material in line 83 maycomprise 4100 barrels per day of the bottoms fractionfrom fractionator 52, 510 barrels vper day of hydrocarbon material from the fractionator I2and 5310 barrels per day of a heavy gasoil in line 90, which gas oil isobtainedfrom the products of cracking in reactor 1.' YIn ordertoaid inthe subse. quent volatilizaton of the material in line 83 and to prevent.cok'ing inthe furnace, steam maybe added to `the material in line "83through line 89 by openingvalve 9|. The hydrocarbon material in line 83after -passage through furnace 851s Ncharged through line 9T to` a tarseparatorli f Y from which' a vaporized overhead fraction is rel movedby liney 94 and an unvaporzed liquid fraction removedby line 9.5, whichfractionmay.

Afor example, be about 23pe1f cent of the charge introduced by 'line 92.The unvaporized liquid fraction may be directed to'storage through'line96 by opening valve 91 orV it may-be directed to a deasphaltizing zone98fby openingyalvev 99 and passing it through lineI0|-.-Indeasphaltizing zone 98 which may employ propane deasphaltizingor vacuum distillation to remove the heavy asphaltic material, thematerial from line |0I is separated into catalytic cracking stock whichis A removed from the deasphaltizing zone 98 by line generally below0.05 per cent, 1s removed from the 45 |02 and the asphaltic fractionwhich is removed from this zone byline |03.- When propanefdeasphaltizing is usec, as in theexeinplary operation, the "conditionsof deasphaltization are selected to produce 1370 barrels per day`of aclean charge stock having an end point of about'1100 F; The overheadfraction from the tar separator Y in line 94 and the deasphaltizedcracking stock in line |02 are passed through heating coils |04 and |05in furnace |06 and thence charged to reactor 1 by lines I3 and I4. Thehydrocarbon material cracked in reactor 1 under the conditionsdescribedfabove is fractionated bylfractionator I6 so as to produce acracked gasoline fraction amounting, in the exemplary operation, toabout 35 to 70 volume per cent of the fresh oil feed. introduced toreactor 1. The gasoline from the fractionator in line I 01 is thereafterappropriate'- ly processed such as by stabilization and removal of fixedgases and by Washing with a solution of caustic, A light gas oilfraction is removed from g I -fractionator I6 by line ||0, a, heavy gasoil frac'- tion by line |08 and a bottoms fraction by line |09. Theheavy gas oil fraction may, if desired, be recycled to'the crackingreactor l by means of unes so and a1,.va1ves aan and ua being ap-Ipropriately manipulated. i

ln order 'to illustrate the present invention but not'to be construed asa limitation thereof, the

75 following specific examplesme given:

tion and tarry bottoms in a tar-separator, the

tarry bottoms deasphaltized using propane, and thedeasphaltizedsxnaterial combined with the tar separator overhead'to`yield a heavy fraction for cracking. The properties of the crude oiland liquid fractions were as follows:

1 Vacuum distillation corrected to atmospheric pressure.

The light fraction and the heavy fraction were separately charged toreactors containing moving beds of freshly regenerated active crackingcatalyst having less than 0.2 weight per cent of residual carbonthereon. The catalyst used was in the form of beads of calcinedsynthetic 10W a1- kali silica-alumina hydrogel prepared in a mannerknownto the art and having a CAT-A activity index of about 33. The lightfraction was charged to the bottom of a desulfurization reactor incounter-current relationship to the moving bed of catalyst; the heavyfraction being charged to the cracking reactor in mixed phase conditionat the top of the catalyst bed for concurrent ow with the moving bed ofcatalyst. 'I'he temperature of the catalyst charged to thedesulfurization reactor was about 755 F., which is approximately 220? F.lower than the average temperature of the catalyst followingregeneration and represents a removal of 110,000 B. t. u. per ton ofcatalyst by cooling. The conditions of operation are given in thefollowing table:

TABLE 1B Operation Desltlilgriza Cracking Light Heavy Charge FractionFraction Space rate. total charge l. 2 1.21 Fresh fced 0.50 Recycle gasoil 0. 71 Catalyst to oil ratio, based on total charge 0.4 1.53Temperatures, F.:

Catal st inlet 755 975 Oil in et 750 805 Average of reactor 735 865Catalyst outlet-- 7 855 Pressure, pounds/sq. in. gauge 10 l0 Catalystcirculating through reactor (tons/hour) 8 100 Coke deposited oncatalyst, weight per cent based on catalyst l. 3.0 C; and lighter,weight per cent oi total oil charged 0. 9 Coke. weight por cent of totaloil charged. 0. 4, Liquid recovery, volume per cent of charge 102. 2 94.0

Catalyst was removed from the desulfurization reactor and from `thecracking reactor and regeneration eiected in the type of regeneratorreferred to above. under conditions such that the residual coke was lessthan 0.2 weight per cent; the catalyst being thus rendered suitable forreuse in the desulfurization and cracking reactors.

The products from the desulfurization and cracking reactors werefractionated separately; the yields and properties being given below.The properties of the straight run gasoline present in the untreatedlight fraction are given for comparison.

TABLE IC Desulfurzatron Diesel fue] cut Gasoline l (boiling above Igasoline) Properties In In Prod- In In Prod- Feed uctl Feed uct Gravity,API 60.1 58.5 36. 5 35. 8 Distillation, ASTM,

Intnl 124 130 412 412 178 183 442 441 262 262 405 482 333 335i 553 547359' 38S 581 034 50. 4 58. 2 58. 68. 0 67. 6 77. 2 50. 7 59. 3 57. 5 68.9 3 cc. TEL.-. 67.3 78. 2 Sulfur, weight percent. 0. l2 0. 02 0. 93 0.57 Anilno Point, F 143 144 Diesel Index 52. 3 5l. Yield, Volume percentof charge l. 49. 2 58. 2 49. 6 41.

l Based on removal of butanes and lighter; all gasolines washed with asolution of caustic. 1

2 Based on butano-free lecd stock.

TABLE ID Craclcmg Light Heavy Properties Gasoline l Catalytic CatalyticGas Oil Gas Oil I. Gravity, API.. 56. 5 18. 2 0. 3 Distillation, ASTMF.:

Initial 94 442 500 132 462 590 242 476 742 378 504 950 End Point 4m 53095% at 990 Octane Numbers R--M, clear-- 80. l +1 cc. T 82. 5 i +3 cc.TEL. 84. 4 CRF-R, clear.-- 91. l +1 cc. TEL.- 94. 5 +3 cc. TEL 97.3 Reidvapor pressure, po ds per sq. in l0 Sulfur, weight percent 0. 18 2 67 3.40 Amline point, F 25 103 Diesel index 4. 5 Yicld, volume percentoliresb feed 63. 8 4. 6 l0. 6

l Washed with a solution of caustic.

By operating the desulfurization and cracking reactors in conjunctionwith a single regenerator under the above conditions, the catalyst fromthe desulfurization reactor, which is only about 7% of the totalcatalyst, adds only 2.6% to the total amount of coke burned, and,although F. cooler than the catalyst from the cracking reactor, lowersthe temperature of the latter only 10 F. when admixed therewith.

'I-he gasoline from the desul'furization and cracking operations, whenblended in amounts proportional to the relative amounts of the chargesin thecrude oil and with the addition of 3 cc. TEL, yield a gasolinehaving about 83.0

"a CFR-M and 89. CFR-R. A gasoline blended in 13 similar manner from theuntreated straight run gasoline described in Table IC and thecatalytically cracked gasoline has an octane number l 5 (with 3 cc.TEL')in contrast to a blend of unn treated and cracked gasoline blended onthesame Crude oil from the Slaughter eld (West basis which has an octanenumber (CFR-M) o f Texas) was distilled to produce the fractions 76.8(with3cc. TEL).

rties:

' f'. having the following prope 1 6 i MPICE m TABLE IIA diesel fuel cutwas prepared from the crude/` ioil of Example II by distillation and hadthe fol- Pmpertles l Llglomcin I lownlg properties:

15 -TABLEIIIA v Gayle, API -B--L 525 .5 Y Gravity, "A1=1 AA -v 32.3ffgggg'tgtf; g 12 wof M1333A Boiling range, ASTM F v. 464 to 656 Octanenumher f 50 9 Sulfur, lWe1ght percent-; 1.43 Cma cr" et 2:::222222:Anillne point, F- .f i. 140 Yield, volume percent-; 3&5 `48.9 Q0 Dieselindex 45.2 Cetane 2knumber i 48.6

'Ihe light fraction was desulfurizedand the heavy fraction cracked in asimilar manner, including type and activity of catalyst, td thatdescribed in connection with Example I except the temperature 0`f thecatalyst charged toi-both -Y operations was in the rangeof 940 to 975 F;(approximately the exit temperature of the regenerator) and the lightfraction was passed, Catalyst to 011 ratio g 0,32 through the reactor inconcurrent relationshipr-BO TeggperatresFJf t 2 to the moving bed ofcatalyst. The conditions .Catalyst inlt (estimated) 970 of theoperations were as follows: 2 0i1"in1et 355 Average of reactor l 840TABLE IIB catalyst outlet 2- 830 2 35 catalyst circulation, tons/hoer1 5Operation Destlilllfi' Cracking Coke deposited on catalyst, weightpercent based on catalyst Y 2.4 Ca and lighter, weight percent of oilcharged 1.8 Charge Liglitom Heat'nfrac' Coke formed, Weightfpercent o` foil charg'ed 0.9

K 40 1 Based on 12,000 barrels of crude oil 'charged per day.spalgrffffealchafge 1-6 g: The operation produced a synthetic` crudeRecycle gos oil. 1.57 which, when distilled; yielded 22.5 volumeperggggftfmsed ontotalchage# 0-41 208 cent (based on original cut) ofmotorgasoline Catalyst inlet 94o :om 94o to 975 having an octane number(CFR-M) of 78.8 (clear) ggelrgeF-f--r-c-t g ggg 45 and 83.3 (with 3 oo.TEL) and 74.5 volume per- Caialyst ouden 84o 895 cent (based on originaldiesel cut) of desulfurized gslgg' gggigggfgl diesel fuel having thefollowing properties:

reactor 1 8. 5 250 Coke deposited on catalyst, Weglltper v TABLE IIIC iofir;antennae: f ffl 50 Gravity, API 33.2.6 Bolling range, ASTM "F 460to 680 l Based on a crude oil charge o! 12,000 barrels per day. Sulfurweghto percent -i L09 As in the previous example, regeneration of thelllegt F``.' *2"*- gli catalyst removed from the desulfurization and lCetane mimi-3; 49's from the cracking zones was eiected in a regeln-' 5Fs I erator whose temperatures were controlled rby in: direct heattransfer. In the present case, mixfture of the two streams of catalystfrom `th`desulfurization and cracking zones results in vrtually nochange in the temperature of the cata` lyst from the cracking zone (lessthan 2 F.) and' the coke on the catalystfrom the desulfurization zoneadds less than 1% to the total amount of coke burned in the regenerator.

The desulfurized light fraction was distilled yield 94 volume per centof debutanized motor gasoline, having a boiling range of 140 to 408 F.and an unleaded octane number (CFRf-M) of 56.2 and an octane number of74.5 with 3 cc. TEL. Thesynthetic crude from the cracking operation vyielded, on distillation, about 60.5 volume per cent Vof motor gasolineand 10.5 volume percent of fuel oil (based on vthe amount {of fresh oilcharged to the reactor), the motor gasoline having ari octane number(CFRf-M) of`81 (clear) and l85.6 (with 3 cc. TELL blended from thedesulfurized and cracked products in the relative proportions in whichthey were produced has. an octanenumber (CFR-M) of 81.2

fPheabove cut was contacted in a pilot plant withicatalystof the typedescribed in Example I in an operation equivalent tothe following con-`2:'`ditions ina commercial size' moving bed reactor:

's T ABLE H113 When the commercial size desulfurization re` ample II,there isvproduced not only a desulfurized dieselfuel :fraction of asgood.v engine quality vas the virgin4 fraction, but also a quantityofhigh octane gasoline which considerably augments that'produced in rthecracking reactor.

In the specification, the fraction boiling between 400" and 750 F. has,for-convenience and brevity, been referred to a diesel fuel fraction. Iti-stobe understood, however, that this fraction may be usedjor otherpurposes where its composition and boiling range lare suitable. Thus allor a part of the 400 to 750 F. fraction may be used I' l as a'tractorfuel, fuel for jet engines and gas turbines, a burning distillate orkerosene, a high grade fuel oil and the like.

Obviously many modifications and varisi'tow7 of :s the invention ashereinbefore set forth nay be motor gasoline 15 made without departingfrom the spirit and scope thereof and therefore only such limitation:should be imposed as are indicated in the ap- -pended claims.

I claim as my invention:

1. The process of refining a, crude petroleum oil having a sulfurcontent of 1 per cent by weight or greater in the 400 to 1000 F.fraction which comprises fractionating said crude into a rlightdistillate consisting of motor gasoline and diesel fuel and a heavyresidual fraction, removing the asphaltic portion from said heavyfraction, passing said light distillate through a first conversion zone,introducing freshly regenerated fluent active cracking catalyst to saidfirst conversion zone, maintaining mild conversion conditions in saidfirst conversion zone such that the coke produced from said lightdistillate is in the range of 0.5 to 2.0 per cent by weight and theamount of gas lighter than butanes produced from said light distillateis in the range of 0.8 to 3.5 per cent by weight, passing thedeasphaltized heavy fraction through a second conversion zone, in-

troducing freshly regenerated fluent active cracking catalyst to saidsecond conversion zone in an amount substantially greater than theamount introduced to said first conversion zone, maintaining crackingconditions in said second conversion'zone so as to effect cracking ofsaid heavy fraction to at least per cent of motor gasoline based on theamount of fresh feed to said zone; removing coked catalyst from said rstand second conversion zones, regenerating a mixture of coked catalystfrom the first and second conversion zones in a regeneration zoneadapted to remove excess heat by indirect heat transfer, removingfreshly regenerated catalyst from said regeneration zone, returningfreshly regenerated catalyst to said rst and second conversion zones,separating the products from said first conversion zone into gasolineand diesel fuel fractions, separating the products from said secondconversion zone into gasoline and other fractions, and blending thegasoline fractions from the first and second conversion zones to yield agasoline of high lead susceptibility.

2. The process of claim 1 in which the amount of catalyst passed throughsaid first conversion zone is less than 25 per cent of the totalcatalyst regenerated.

3. The process of claim 1 in which the amount of catalyst passed throughsaid first conversion zone is less than 10 per cent of thev totalcatalyst regenerated.

4. The process of claim 1 in which the fluent catalyst moves through thetwo conversion zones and through the regeneration zone as movingnon-turbulent beds.

5. The process of refining a crude petroleum oil having a sulfur contentof 1 percent by weight or greater in the 400 to 1000 F. fraction whichcomprises fractionating said crude into a light distillate consisting ofmotor gasoline and diesel fuel and having an end point below about 750F. and a. heavy fraction comprising the remainder of said crude, heatingsaid heavy fraction to a temperature in the range of 800 to 900 F. andseparating said heavy fraction into a vaporous fraction and an asphaltcontaining liquid fraction, removing asphalt from said liquid fraction,passing said light distillate through a downwardly moving non-turbulentbed of catalyst in a first convension zone, introducing freshlyregenerated fluent active cracking catalyst to said first conversionzone in amounts such that a cata.-

16 lyst to oil ratio of less than 0.5 and greater than 0.05 is produced,maintaining mild conversion conditions in said first conversion zonesuch that the coke produced from said light distillate is in the rangeof 0.5 to 2.0 percent by weight and the amount of gas lighter thanbutanes produced from said light distillate is in the range of 0.8 to3.5 percent by weight, passing the deasphaltized liquid fraction andsaid vaporous fraction through. a downwardly moving nonturbulent bed ofcatalyst in a second conversion zone. introducing freshly regeneratedfluent active cracking catalyst to said second conversion zone inamounts such that a catalyst to oil ratio of greater than 1.5 isproduced, maintaining cracking conditions in said second conversion zoneso as to eect cracking of the total hydrocarbons charged to at least 35percent of motor gasoline, removing coked catalyst from said rst andsecond conversion'zones, regenerating a mixture of coked catalyst fromthe rst and second conversion zones in a. regeneration zone adapted toremove excess heat by indirect heat transfer, removing freshlyregenerated catalyst from said regeneration zone, returning freshlyregenerated catalyst to said first and second conversion zones,separating gasoline and diesel fuel from the products from said firstconversion zone, said diesel fuel having substantially'the same dieselindex as that of the straight run untreated diesel fuel and having asubstantially lower sulfur content than said untreated diesel fuel,separating gasoline from the products from said second conversion zone,and blending the gasoline fractions from the first and second conversionzones to yield a gasoline of high lead susceptibility.

6. The process of refining a crude petroleum oil having a sulfur contentof 1 percent by weight or greater in the 400 to 1000 F. fraction whichcomprises separating said crude into a light distillate comprisingdieselfuel and having an end point below about 750 F. and a heavyresidual fraction, deasphalting said heavy residual fraction, passingsaid light distillate through a downwardly moving non-turbulent bed ofcatalyst in a first conversion zone, introducing freshly regeneratedfluent active cracking catalyst to said first conversion zone in amountssuch that a catalyst to oil ratio of less than 0.5 and greater than 0.05is produced, maintaining mild conversion conditions in said firstconversion zone such that the coke produced from said light distillateis in the range of 0.5 to 2.0 percent by weight and the amount of gaslighter than butanes produced from said light.- distillate is in therange of 0.8 to 3.5 percent by weight, passing the deasphaltized heavyresidual fraction through a downwardly moving non-turbulent bed ofcatalyst in a second conversion zone, introducing freshly regeneratedfluent active cracking catalyst to said second conversion zone inamounts such that a catalyst to oil ratio of greater than 1.5 isproduced, maintaining cracking conditions in said second conversion zoneso as to effect cracking of the total hydrocarbons charged to at least35 percent of motor gasoline, removing coked catalyst from said firstand second conversion zones, regenerating a mixture of coked catalystfrom the first and second conversion zones in a commonregenerationfzone, removing freshly regenerated catalyst from saidregeneration zone, returning freshly ,regenerated catalyst to said firstand second conversion zones, .separating gasoline and diesel fuel fromthe products from said first conversion zone, said die;e1

fuel having substantially the same diesel index as that of the straightrun untreated diesel fuel and having a substantially lower sulfurcontent than said untreated diesel fuel, separating ygasoline from theproducts from said second conversion zone, and blending the gasolinefractions from the rst and second conversion zones to yield a gasolineof high lead susceptibility.

7. The process of renning a crude petroleum oil having a sulfur contentof l percent by lweight or greater in the 400 to 1000 F. fraction whichcomprises fractlonating said crude into a light distillate comprisingdiesel fuel and having an end point below about' 750 F. and a heavyfraction comprising the remainder of said crude, sep- I arating saidheavy fraction into a vaporous fraction and an asphalt containing liquidfraction,

removing asphalt from said liquid fraction, passing said lightdistillate through a downwardly moving non-turbulent bed of catalyst ina rst conversion zone, introducing freshly regenerated fluent activecracking catalyst to said ilrst conversion zone in amounts such that acatalyst to oil ratio of less than 0.5 and greater than 0.05.15produced, maintaining mild conversion conditions in said firstconversion zone such that the troducing freshly regenerated nuent activecracking catalyst to vsaid second conversion zone in amounts such that acatalyst to oil ratio of greater than 1.5 is produced, maintainingcracking conditions in said second conversion zone so as to effectcracking of the total hydrocarbons charged to at least 35 percent ofmotor gasoline,

removing coked catalyst from said first and second conversion zones,regenerating a mixture of 18 coked catalyst from the nrst and secondconversion zones in a common regeneration zone, removing freshlyregenerated catalyst from said regeneration zone, returning freshlyregenerated catalyst to said first and second conversion zones,separating gasoline and diesel fuel from the products from said iirstconversion zone, said diesel fuel having substantially the same dieselindex as that of the straight run luntreated diesel fuel and having asubstantially lower sulfur content than said untreated diesel fuel,separating gasoline from the products from said second conversion zone,and blending the gasolineA fractions from the first and secondconversion zones to yield a gasoline of high lead susceptibility.

JOHN E. FORD. Jn.

REFERENCES CITED The following references are of record in the fue ofthis'patent:

UNITED STATES PATENTS Number Name Date 2,290,580 Degnen et al. July 2l,1942 .2,377,613 Conn z June 5, 1945 2,409,353 Guiliani et al. Oct. 15,l946 2,414,973 Nelson Jan. 28, 1947 2,432,912 Loeb Dec. 16, 1947$438,456 Russell et al Mar. 23. 1948 2,450,724 Grote Oct. 5. 1948 OTHERREFERENCES 1,'1943, pages R-563, 564, 566. 557.

1. THE PROCESS OF REFINING A CRUDE PETROLEUM OIL HAVING A SULFUR CONTENTOF 1 PER CENT BY WEIGHT OR GREATER IN THE 400* TO 1000*F. FRACTION WHICHCOMPRISES FRACTIONATING SAID CRUDE INTO A LIGHT DISTILLATE CONSISTING OFMOTOR GASOLINE AND DIESEL FUEL AND A HEAVY RESIDUAL FRACTION, REMOVINGTHE ASPHALTIC PORTION FROM SAID HEAVY FRACTION, PASSING SAID LIGHTDISTILLATE THROUGH A FIRST CONVERSION ZONE, INTRODUCING FRESHLYREGENERATED FLUENT ACTIVE CRACKING CATALYST TO SAID FIRST CONVERSIONZONE, MAINTAINING MILD CONVERSION CONDITIONS IN SAID FIRST CONVERSIONZONE SUCH THAT THE COKE PRODUCED FROM SAID LIGHT DISTILLATE IS IN THERANGE OF 0.5 TO 2.0 PER CENT BY WEIGHT AND THE AMOUNT OF GAS LIGHTERTHAN BUTANES PRODUCED FROM SAID LIGHT DISTILLATE IS IN THE RANGE OF 0.8TO 3.5 PER CENT BY WEIGHT, PASSING THE DEASPHALTIZED HEAVY FRACTIONTHROUGH A SECOND CONVERSION ZONE, INTRODUCING FRESHLY REGENERATED FLUENTACTIVE CRACKING CATALYST TO SAID SECOND CONVERSION ZONE IN AN AMOUNTSUBSTANTIALLY GREATER THAN THE AMOUNT INTRODUCED TO SAID FIRSTCONVERSION ZONE, MAINTAINING CRACKING CONDITIONS IN SAID SECONDCONVERSION ZONE SO AS TO EFFECT CRACKING OF SAID HEAVY FRACTION TO ATLEAST 35 PER CENT OF MOTOR GASOLINE BASED ON THE AMOUNT OF FRESH FEED TOSAID ZONE; REMOVING COKED CATALYST FROM SAID FIRST AND SECOND CONVERSIONZONES, REGENERATING A MIXTURE OF COKED CATALYST FROM THE FIRST ANDSECOND CONVERSION ZONES IN A REGENERATION ZONE ADAPTED TO REMOVE EXCESSHEAT BY INDIRECT HEAT TRANSFER, REMOVING FRESHLY REGENERATED CATALYSTFROM SAID REGENERATION ZONE, RETURNING FRESHLY REGENERATED CATALYST TOSAID FIRST AND SECOND CONVERSION ZONES, SEPARATING THE PRODUCTS FROMSAID FIRST CONVERSION ZONE INTO GASOLINE AND DIESEL FUEL FRACTIONS,SEPARATING THE PRODUCTS FROM SAID SECOND CONVERSION ZONE INTO GASOLINEAND OTHER FRACTIONS, AND BLENDING THE GASOLINE FRACTIONS FROM THE FIRSTAND SECOND CONVERSION ZONES TO YIELD A GASOLINE OF HIGH LEADSUSCEPTIBILITY.